Metal oxide/silica composite, and a cosmetic preparation comprising thereof

ABSTRACT

The object of this invention is to provide a UV protective powder, and a cosmetic preparation in which the dispersibility of metal oxide is kept at a high level, and the UV protection activity and transparency of the preparation are satisfactorily maintained. 
     A metal oxide/silica composite wherein metal oxide particles whose primary particle diameter is 1-1000 nm are co-dispersed finely with silica particles, and the metal oxide particles exist substantially as primary particles in the composite. The composite is preferably obtained by mixing (1) a dispersion comprising a silica sol where silica particles have a primary particle diameter of 1-150 nm, and (2) fine particles of metal oxide whose primary particle diameter is 1-1000 nm, or a sol of the same metal oxide, and the metal oxide existing as fine particles or a sol preferably consists of one, or two or more selected from a group consisting of titanium oxide, zinc oxide and cerium oxide. Also a cosmetic preparation comprising thereof is provided.

RELATED APPLICATIONS

This application is 371 of PCT/JP01/08308 filed on Sep. 25, 2001.

This application claims the priority based on Japanese PatentApplication No. 2000-290846 filed on Sep. 25, 2000, which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a metal oxide/silica composite and acosmetic preparation comprising thereof, particularly to an improvementof dispersibility of the metal oxide.

2. Background Arts

When compared with ultra-violet (UV) ray absorbing agents represented byoctylmethoxycinnamate, UV protective powders such as titanium oxide orzinc oxide are advantageous in their safety while they aredisadvantageous in their giving a whitish shade when applied on theskin, which may cause an artificial finish. To meet this problem, whenparticles of titanium oxide are coated with a transparent powder such assilica or the like, it is known the transparency of those particles isimproved. It is also known that, when ultra-fine particles of titaniumoxide or zinc oxide or a sol solution of such a compound is added to acosmetic preparation, the transparency of the preparation is moreemphasized as compared with the same preparation to which a conventionalpowder of zinc oxide or titanium oxide has been added.

However, when particles of titanium oxide are coated with a transparentpowder of silica or the like, the resulting powder tends to lose its UVprotection activity in proportion with the increased fraction of thecoat. It has been established that, when ultra-fine particles oftitanium oxide or of zinc oxide, or a sol solution of such a compound isadded to a cosmetic preparation, the particles or the sol settles on thebottom over time, to aggregate there, which may act as a factorresponsible for reducing the UV protection activity of the preparation,or for interfering with its stability.

DISCLOSURE OF INVENTION

The object of this invention is to provide a UV protective powder, and acosmetic preparation in which the dispersibility of metal oxide is keptat a high level, and the UV protection activity and transparency of thepreparation are satisfactorily maintained.

The present inventors obtained a gel by directly mixing a fine particledispersion of metal oxide having a UV protection activity such astitanium oxide, zinc oxide or cerium oxide, or a sol solution of such acompound with a silica sol, in such a manner as to cause them tocoagulate. Further, the inventors mixed a fine particle dispersion ofthe above metal oxide or its sol solution with a silica sol dispersion,under a pH condition where the two sols will not coagulate; then alteredthe pH by using acid or alkali in such a manner as to cause the two solsto coagulate and deposit, and obtained from the deposit a powder of acomposite of the two substances. The inventors discovered that thepowder has a structure where silica particles and the metal oxideexisting substantially as primary particles intricately intermingle witheach other (finely co-disperse), and has a high transparency and UVprotection activity. Finally, the inventors discovered that a sun-screensupplemented with a powder of this composite gives a natural finish freefrom the artificial whitish shade when applied on the skin, whilekeeping a high UV protection activity, and completed this invention.

The metal oxide/silica composite of this invention is characterized byhaving a structure where metal oxide particles whose primary particlediameter is 1-1000 nm and existing substantially as primary particles inthe composite co-disperse finely with silica particles.

The metal oxide/silica composite of this invention is preferablyobtained by mixing (1) a dispersion comprising a silica sol where silicaparticles have a primary particle diameter of 1-150 nm, and (2) fineparticles of metal oxide whose primary particle diameter is 1-1000 nm,or a sol of the same metal oxide.

Alternatively, the metal oxide/silica composite of this invention ispreferably obtained by mixing the above dispersion with fine particlesof metal oxide or its sol, and altering the pH of the resulting mixturesolution, so as to cause the silica and the metal oxide to aggregate fordeposition.

Still further, for producing the metal oxide/silica composite of thisinvention, the metal oxide existing as fine particles or a solpreferably consists of one, or two or more selected from a groupconsisting of titanium oxide, zinc oxide and cerium oxide.

Still further, for producing the metal oxide/silica composite of thisinvention, the metal oxide/silica composite exists as a gel-likecomposition.

Still further, the metal oxide/silica composite of this invention isobtained by drying the gel-like composition to a powdery composition.

Still further, the metal oxide/silica composite of this inventionpreferably comprises 5-90 wt % metal oxide with respect to the totalweight of the composite.

Still further, the cosmetic preparation of this invention ischaracterized by comprising such a metal oxide/silica composite.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph to show the optical transmissions of a composite oftitanium oxide/silica (Example 1) and of Comparative Example 1.

FIG. 2 is a graph to show the optical transmissions of two composite oftitanium oxide/silica (Examples 1-2 and 1-3).

FIG. 3 is a chart to show an X-ray diffraction pattern of a composite oftitanium oxide/silica (Example 1-2).

FIG. 4 is an SEM (scanning electron microscopy) photomicrograph of acomposite of titanium oxide/silica.

FIG. 5 is a TEM (transmission electron microscopy) photomicrograph of acomposite of titanium oxide/silica.

BEST MODE FOR CARRYING OUT THE INVENTION

The detailed description of this invention will be given below.

The silica sol included in the present invention is a system in whichfine silica colloid particles are uniformly dispersed in a medium. Thecommercially available such system may include “Snowtex” series providedby Nissan Chemical Industries, Ltd. The dispersing medium may includeany solvent including water, isopropanol, methylethylketone, etc., aslong as the solvent does not interfere with the dispersion stability ofsilica particles in the sol. If water is employed as the dispersingmedium, it is possible to control the development of a metaloxide/silica composite so as to produce a highly functional commpositein which particles are more uniformly dispersed than otherwise possible,by choosing an acidic or alkaline silica sol solution in accordance withthe iso-potential point of metal oxide to be mixed which may exist asparticles or as a sol.

Particles of silica in a sol used in this invention have a diameter of1-150 nm, preferably 5-100 nm. If the particles had a larger diameter ora smaller diameter than the above range, those silica particles couldnot smoothly invade the interstices between titania particles, and thuscould not disperse the titania particles uniformly. As a result, titaniaparticles would aggregate themselves while silica particles aggregatethemselves, and the resulting cosmetic preparation would have a reducedUV protection activity, and give a notable artificial white appearancewhen applied on the skin.

The particulate or sol metal oxide mentioned in this invention mayinclude one, or two or more selected from a group consisting of titaniumoxide, zinc oxide and cerium oxide. The metal oxide existing asparticles or as a sol may be obtained as a solid solution consisting oftwo or more selected from a group consisting of titanium oxide, zincoxide and cerium oxide, or as a solid solution consisting of a metaloxide as above with another metal oxide. The primary particles of metaloxide have a diameter of 1-1000 nm, preferably 5-500 nm. If the primaryparticles of metal oxide had a larger diameter than the above range,they would have a reduced tendency for forming a composite with a silicasot, and a reduced UV protection activity by an amount correspondingwith the incremental addition of silica. If the primary particles ofmetal oxide had a smaller diameter than the above range, the resultingcomposite would not give a cosmetic preparation with a high UVprotection activity.

A general acidic or alkaline agent can be employed in the invention as apH adjusting agent for gelation of the metal oxide/silica composite. Asexamples of such an acidic agent, hydrochloric acid, acetic acid, citricacid, sulfuric acid, phosphoric acid, nitric acid and the like areillustrated. Also as examples of such an alkaline agent, sodiumhydroxide, potassium hydroxide, sodium carbonate, potassium carbonate,aqueous ammonia and the like are illustrated.

The fraction of metal oxide in the metal oxide/silica composite of thisinvention is 5-90 wt. %, preferably 25-80 wt. % with respect to thetotal weight of the composite. If the fraction were below the aboverange, no cosmetic preparation based on the composite would give adesired UV protection activity. If the fraction were over the aboverange, particulate or sol metal oxide would aggregate solely bythemselves, and a cosmetic preparation based on the composite would havea reduced UV protection activity contrary to expectation.

The composite is dried being heated at room temperature to 200° C.,preferably in a range of 80-120° C. Drying a composite causes silicacolloids in the sol to be condensed, and titania fine particles to bestably dispersed throughout the sol to be held there. Therefore, it isdesirable to develop a composite while preventing silica sol frommaintaining an initial state.

In the process obtaining a composite of metal oxide or its sol, andsilica sol, the other kind of metal oxide or its sol is alsoincorporated and mixed with them at the same time to obtain a compositewith them. For example, metal oxides or sol thereof such as aluminumoxide(alumina), iron oxide, copper oxide, magnesium oxide, nickel oxide,zirconium oxide, cobalt oxide and the like can be incorporated to obtainthe composite with them. Also metal fine particles of such as goldcolloid particles can be incorporated to obtain the composite with them.

A composite of metal oxide/silica obtained by the invention can be usedwith a hydrophobic treatment by a fatty acid salt such as aluminumstearate, zinc myristate; a fatty acid such as stearic acid, palmiticacid; a wax such as candelilla wax, carnauba wax; modified silicone suchas polyoxyethylene modified silicone, carboxyl modified silicone, aminomodified silicone; silicone oil such as methyl polysiloxane,methylphenyl polysiloxane; dextrin fatty acid ester and the like atneed.

In a cosmetic preparation of the invention, constituents normallyemployed for a cosmetic preparation can be contained in such a mannerthat the effect of the invention is not lost. For example, a solid orsemi-solid oil such as petrolatum, lanolin, ceresin, carnauba wax,candelilla wax and higher alcohol; a liquid oil such as squalane, liquidpetrolatum and ester oil; an oil such as silicone oil; a humectants suchas sodium hyaluronate and glycerin; a surfactant such as cationicsurfactant and non-ionic surfactant; and a pigment, an antiseptic, aperfume, an invigorate agent are suitably contained.

The present invention will be described in detail below by means ofExamples and Comparative Examples, but the scope of this inventionshould not be limited in any way to those Examples. The inventorsmanufactured powders having UV protection activities as represented byExamples 1 to 5 and Comparative Examples 1 to 4 described below.Examples represent mixtures including silica sols, while ComparativeExamples corresponding mixtures with no silica sol added.

EXAMPLE 1-1

A 50 g of Snowtex O (silica sol available from Nissan ChemicalIndustries, Ltd. which contains 20% silica, and in which silica primaryparticles have a diameter of 10-20 nm) and 10 g of TSK-5 (titania solavailable from Ishihara Sangyo Kaisha, Ltd. which contains 30% titaniumoxide particles rutile type having a primary diameter of 10-100 nm) weremixed; to the resulting uniform dispersion was added dropwise 0.1Maqueous solution of sodium hydroxide to bring pH=9; and then a gel-likesubstance was obtained. The substance was filtered and washed with waterfive times or more; and the resulting solid was exposed to a temperatureof 100 to 110° C., to cause moisture to be evaporated. Thus, a powdercomprising a composite of titanium oxide/silica was obtained.

EXAMPLE 1-2

A 15 g of Snowtex O (silica sol available from Nissan ChemicalIndustries, Ltd. which contains 20% silica, and in which silica primaryparticles have a diameter of 10-20 nm) and 268 ml of titania solaquesous solution (which has pH=1, and contains 8 g of TiO₂ anatase typewhich has a primary particle diameter of 10-100 nm) were mixed; to theresulting uniform dispersion was added dropwise 0.1M aqueous solution ofpotassium hydroxide to bring pH=8.5; and then a gel-like substance wasobtained. The substance was filtered and washed with water five times ormore; the resulting solid was exposed to a temperature of 90° C., tocause moisture to be evaporated. Thus, a powder comprising a compositeof titanium oxide/silica was obtained.

EXAMPLE 1-3

A 40 g of Snowtex O (silica sol available from Nissan ChemicalIndustries, Ltd. which contains 20% silica, and in which silica primaryparticles have a diameter of 10-20 nm) and 268 ml of titania solaquesous solution (which has pH=1, and contains 8 g of TiO2 anatase typewhich has a primary particle diameter of 10-100 nm) were mixed; to theresulting uniform dispersion was added dropwise 0.1M aqueous solution ofpotassium hydroxide to bring pH=8.5; and then a gel-like substance wasobtained. The substance was filtered and washed with water five times ormore; and the resulting solid was exposed to a temperature of 90° C., tocause moisture to be evaporated. Thus, a powder comprising a compositeof titanium oxide/silica was obtained.

EXAMPLE 2

A 100 g of Snowtex 30 (silica sol available from Nissan ChemicalIndustries, Ltd. which contains 30% silica, and in which silica primaryparticles have a diameter of 10-20 nm) and 10 g of TSK-5 were mixed; tothe resulting dispersion was added dropwise 0.5M diluted aqueoussolution of hydrochloric acid to bring pH=7-8; and then a gel wasobtained. The gel was filtered and washed with water five times or more;and the resulting solid was exposed to a temperature of 100 to 110° C.for drying. Thus, a powder comprising a composite of titaniumoxide/silica was obtained.

EXAMPLE 3

A powder of zinc oxide as described in an Example of WO99/25654 (whichhas a primary particle diameter of 50-100 nm) was allowed to disperse inSnowtex XL (silica sol available from Nissan Chemical Industries, Ltd.,which contains 40% silica, and in which silica primary particles have adiameter of 40-60 nm) to give a ratio of silica sol: zinc oxide=25:75.To the dispersion was added 0.1M diluted aqueous solution ofhydrochloric acid to give a gel-like substance which was then dried andpulverized. The resulting powder was washed with water and dried again.Thus, a powder of a composite of zinc oxide/silica was obtained.

EXAMPLE 4

A dispersion comprising silica sol/isopropyl alcohol (IPA-ST, 30% silicacontent, primary particle diameter of 10-20 nm) was mixed with a sol ofcerium oxide (primary particle diameter of 50-100 nm) to give a ratio ofsilica gel:cerium oxide=35:65. The resulting dispersion was dried whilebeing stirred with a kneader. Thus, a powder of a composite of ceriumoxide/silica was obtained.

EXAMPLE 5

A 15 g of Snowtex O (silica sol available from Nissan ChemicalIndustries, Ltd.) and 30 g of alumina sol 100 (which contains 10-11%alumina) were mixed. To the mixture was added 100 g of titania sol(TSK-5), and to the resulting uniform dispersion was added dropwise 0.2Maqueous solution of sodium hydroxide to bring pH=7, which produced agel-like substance. The substance was filtered and washed with waterfive times or more; and the resulting solid was exposed to a temperatureof 100-110° C., to cause moisture to be evaporated. Thus, a powdercomprising a composite of titanium oxide/silica/alumina was obtained.

COMPARATIVE EXAMPLE 1

Particulate titanium oxide (titanium oxide 100AL, available from TaycaCorporation, primary particle diameter of 30 nm) and Aerosil #200(silica gel available from Nippon Aerosil Co., Ltd., primary particlediameter of 12 nm) were mixed to give a ratio of 3:1, and the yield wasstirred for 1 minute with a mixer. The resulting preparation was used asComparative Example 1.

COMPARATIVE EXAMPLE 2

To a solution which had been obtained by dissolving 30 g of aqueousglass in 150 g of water was added 100 g of titania sol (TSK-5). To theresulting solution was added 0.5M diluted aqueous solution ofhydrochloric acid to bring pH=7-8. The yield was dried by heating, whilebeing stirred with a kneader. The resulting powder was washed withwater, dried and pulverized. The yield was used as Comparative Example2.

COMPARATIVE EXAMPLE 3

A 20 g of sodium metasilicate was dissolved in 300 g of water; to theresulting solution was added a powder of zinc oxide as described in anExample of WO99/25654 for dispersion; and to the resulting solution wasadded 1M diluted aqueous solution of hydrochloric acid to bring pH=8.The resulting dispersion was filtered, washed and dried to give a powderwhich was used as Comparative Example 3.

COMPARATIVE EXAMPLE 4

A cerium sol and tetraethylorthosilicate were mixed to give a ratio ofcerium oxide:silica=65:35. The mixture was heated at 80° C. for 12 hoursfor hydrolysis. The reaction product was filtered, washed, dried andpulverized. The yield was used as Comparative Example 4.

The present inventors made following comparison experiments using theabove powders.

Comparison Experiment 1-1

The inventors compared Example 1-1, a powder of a titanium oxide/silicacomposite of this invention, with Comparative Example 1, a powder of ablend of titanium oxide particles and silica particles.

The powders of Example 1-1 and Comparative Example 1 were added tocastor oil to give a ratio of powder:castor oil=1:9. From each mixture,a slurry comprising the powder and castor oil was prepared. The slurrywas kneaded with a kneader based on three rollers. After kneading, theslurry was applied on a quartz plate with an applicator to produce afilm of 5 μm thickness thereupon. The UV transmission through the filmwas measured with a spectrophotometer (U-3410, Hitachi, Ltd.).

FIG. 1 shows the measurement results of the slurry obtained in theComparison Experiment 1. Comparison of the results in FIG. 1 shows that,although the transmission through Example 1-1 of UVB having a wavelengthof 290-320 nm is practically the same with the counterpart forComparative Example 1, the transmission through Example 1-1 of rayshaving a visible wavelength is generally higher than the counterpart forComparative Example 1. This suggests Example 1-1, when compared withComparative Example 1, has a similar UV protection activity but a highertransparency to visible rays, thus being capable of exercising a highercosmetic function which may be ascribed to the more intimate integrationof titanium oxide particles with silica particles.

As in Comparative Example 1, Examples 1-2 and 1-3, each comprising atitanium oxide/silica composite obtained from a titanium oxide sol and asilica sol, were added to castor oil to give slurries. The slurry wasallowed to form a thin film. The transmission of UV rays through thefilm was measured with a spectrophotometer (U-3410, Hitachi).

FIG. 2 shows the measurement results. It is seen from the figure thatboth of Examples 1-2 and 1-3 give powders as excellent in protectingagainst UV rays, and in transparency as Example 1-1 owing to theintimate integration of titanium oxide particles with silica particles.

X-Ray Diffraction Pattern of the Commposite

Next, the inventors applied an X-ray analysis to the metal oxide/silicacomposite. FIG. 3 shows an X-ray diffraction pattern of a titaniumoxide/silica composite represented by Example 1-2. From the result shownin FIG. 3, it is seen that titanium oxide does not give any notable peakexcepting a main peak. This suggests that titanium oxide exists, in thetitanium oxide/silica composite, substantially as primary particlesdispersed therethrough.

The Content of Metal Oxide in the Composite

The inventors prepared titanium oxide/silica composite havingcompositions as described in Table 1 below, and studied how the contentof metal oxide affects the performance of the composite. In accordancewith Comparison Experiment 1, the transmission of rays therethrough at awavelength of 310 nm was measured. The UV protection activity of thefilm was evaluated and ranked as follows.

(Ranking of the Protection Activity)

-   ⊚: Transmission at 310 nm is less than 10%.-   ◯: Transmission at 310 nm is not less than 10% but less than 20%.-   Δ: Transmission at 310 nm is not less than 20% but less than 30%-   X: Transmission at 310 nm is not less than 30%.

TABLE 1 amount of titanium oxide amount of silica (wt. %) (wt. %) UVprotection activity  1 99 X  5 95 ◯ 10 90 Δ 30 70 ◯ 50 50 ⊚ 75 25 ⊚ 8515 ◯ 90 10 ◯ 95  5 Δ

From the results of Table 1, it is seen that the content of metal oxidein the metal oxide/silica composite should be 5-90 wt. %, preferably25-80 wt. %.

Next, the inventors studied the relationship between the content oftitanium oxide in a titanium oxide/silica composite and the half-valuewidth for d=3.25 (peak representing a (hk1)=(110) surface of rutile typetitanium oxide).

TABLE 2 the half-value width for d = 3.25 content of titanium oxide(100% titanium oxide is normalized to be 1.)  17% 1.40  60% 1.22  88%1.11 100% 1.00

From the results of Table 2 it is seen that the half-value widthincreases with the reduction of titanium oxide content in the composite,suggesting the crystalline nature of titanium oxide is impaired. Thissuggests that titanium oxide exists, in the titanium oxide/silicacomposite, substantially as primary particles dispersed therethrough.

FIG. 4 shows an SEM photomicrograph of a titanium oxide/silica compositeof this invention (Example 1-2). From FIG. 4 it is confirmed thattitanium oxide and silica exist substantially as primary particles, andintermingle with each other to give a uniform dispersion.

Specific Surface Area of the Composite

Next, the inventors studied the specific surface area of a titaniumoxide/silica composite. The results are shown in Table 3. The resultsobtained from the constituents are listed under (1) and (2), the resultfrom the composite under (3) and a theoretical value expected for thecomposite under (4).

TABLE 3 specific surface area (m²/g) (1) dried titania sol 265.7 (2)silica sol 239.8 (3) the titanium oxide/silica composite 291.3 of theinvention (titanium oxide:silica = 70:30) (4) the titanium oxide/silicacomposite 257.9 via calculation from (1) and (2)

From the results of Table 3, it is seen that the measured specificsurface area of the titanium oxide/silica composite is larger than thetheoretical counterpart of the same composite obtained via calculationusing the corresponding values of its constituents, i.e., titania soland silica sol. It can be said from this that the two kinds of particlesintimately mix with each other to form a uniform composite which ratherprevents the two kinds of particles from agglutinating to each other.

Comparison Experiment 2

The inventors prepared O/W emulsified sunscreens using the powdersobtained in Example 2 and in Comparative Example 2. Then, they comparedthe cosmetic preparations containing the powdery composites preparedfrom a titanium oxide sol and a silica sol as in Example 2, and thecosmetic preparations containing powdery mixtures prepared without usinga silica sol as in Comparative Example 2. The prescription of theexperimental cosmetic preparation is as shown in Table 4, and itspreparation process is given below.

TABLE 4 Example 6 O/W emulsified sunscreen  1. Powder of Example 2 12 2. Zinc white 5  3. Stearic acid 2  4. Cetyl alcohol 1  5. Petroleum 5 6. Silicone oil 2  7. Liquid petroleum 10  8. Glyceryl monostearate 1(self-emulsifying type)  9. Polyoxyethylene (25 mol) mono oleate 1 10.Polyethyleneglycol 1500 5 11. Beegum 0.5 12. Purified water 55.5 13.Perfume suitable amount 14. Antiseptic suitable amountPreparation Process

To constituent 12 was added constituent 10, which was dissolved byheating, and constituent 11 was added, and the mixture was stirred witha homomixer to give a uniform dispersion, which was then maintained at70° C. The yield was used as a water phase. Constituents 3-9 were mixedwith constituents 13 and 14, which was then heated for dissolution andmaintained at 70° C. To the water phase were added powders ofconstituents 1 and 2, and were dispersed with a homomixer. To thisdispersion was added the oil phase, which was uniformly emulsified witha homomixer. After emulsification, the emulsion was cooled to 35° C.while being stirred. Thus, a sunscreen of Example 6 was obtained.

The same process as used to produce the O/W emulsified sunscreen ofExample 6 was employed, except that a powder obtained in ComparativeExample 2 was used, instead of a powder obtained in Example 2, to give apowder of Comparative Example 5. Example 6 and Comparative Example 5were applied to the skin, and the resulting stains were evaluated byvision for how notable their whiteness is. The evaluation was ranked asfollows. The results are shown in Table 5.

(Ranking of Transparency)

-   ◯: transparency present-   Δ: somewhat notable whiteness, and slightly low transparency-   X: notable whiteness, and no transparency

TABLE 5 Example 6 Comparative Example 5 Transparency ◯ Δ

From the results of Table 5 it is seen that Example 6 including acomposite comprising titanium oxide of Example 2 as primary particlesand silica particles both of which disperse intimately into each other,provides a sunscreen whose whiteness looks natural and plain even whenobserved immediately after its application to the skin, and thus ensuresa fine finish. In contrast, Comparative Example 5 containing a powder ofComparative Example 2 gives a notable white when applied to the skin.Moreover, it is more difficult to extend Comparative Example 5 uniformlyover the skin. From this it is obvious that if silica sol were not addedduring the manufacture of a composite, particles of titanium oxide couldnot disperse to the same extent as observed in the composite of thisinvention.

Comparison Experiment 3

The inventors prepared oily stick foundations using powders obtained inExample 3 and in Comparative Example 3. Thus, they compared a cosmeticpreparation obtained from a powder of this invention prepared in Example3, i.e., a composite prepared from particulate zinc oxide and a silicasol, with a cosmetic preparation based on a powder prepared inComparative Example 3, i.e., a similar composite with, however, nosilica sol added. The prescription of the experimental cosmeticpreparation is as shown in Table 6, and its preparation process is givenbelow.

TABLE 6 Example 7 Oily stick foundation (Powder Part)  1. Powder ofExample 3 8  2. Talc 2.8  3. Kaolin 16  4. Mica 3  5. Titanium dioxide16  6. Red iron oxide 1  7. Yellow iron oxide 3  8. Black iron oxide 0.2(Oil Part)  9. Solid Parrafin 3 10. Microcrystalline wax 7 11. Petroleum15 12. Dimethyl polysiloxane 3 13. Squalane 5 14. Isopropyl palmitate 1715. Antioxidant suitable amount 16. Perfume suitable amountPreparation Process

Constituents 9-15 were kept at 85° C. for dissolution, to which wasadded a powder well mixed with stirring. The yield was then pulverizedwith a colloidal mill for dispersion. Then, constituent 16 was added tothe mixture, and the resulting yield, after deaeration, was poured intoa vessel at 70° C., and cooled to give a foundation of Example 7.

The same process as used to produce the oily stick foundation of Example7 was employed, except that a powder obtained in Comparative Example 3was used, instead of a powder obtained in Example 3, to give apreparation of Comparative Example 6.

Example 7 and Comparative Example 6 were applied to the skin, and theresulting stains were evaluated immediately after application by visionfor how notable their whiteness is. The evaluation was ranked as above.The results are shown in Table 7.

TABLE 7 Example 7 Comparative Example 6 Transparency ◯ Δ

From the results of Table 7 it is seen that Example 7 comprising acomposite of titanium oxide of Example 3 provides a foundation whosewhiteness looks natural and plain even when observed immediately afterits application to the skin, and thus ensures a fine finish. Incontrast, Comparative Example 3 containing a powder of ComparativeExample 3 gives a notable white when applied to the skin. Moreover, itis more difficult to extend Comparative Example 6 uniformly over theskin. From this it is obvious that addition of silica sol improves thedispersibility of zinc oxide as well as of titanium oxide.

Comparison Experiment 4

The inventors prepared oily stick foundations using powders obtained inExample 4 and in Comparative Example 4. The prescription of theexperimental cosmetic preparation is as shown in Table 8, and itspreparation process is given below.

The inventors prepared oily stick foundations using powders obtained inExample 4 and in Comparative Example 4. Then, they compared a cosmeticpreparation obtained from a powder of this invention prepared in Example3, i.e., a composite prepared from a cerium oxide sol and a silica sol,with a cosmetic preparation based on a powder prepared in ComparativeExample 4, i.e., a similar composite with, however, no silica sol added.The prescription of the experimental cosmetic preparation is as shown inTable 8, and its preparation process is given below.

TABLE 8 Example 8 Oily stick foundation (Powder Part)  1. Powder ofExample 4 8  2. Talc 2.8  3. Kaolin 16  4. Mica 3  5. Titanium dioxide16  6. Red iron oxide 1  7. Yellow iron oxide 3  8. Black iron oxide 0.2(Oil Part)  9. Solid Parrafin 3 10. Microcrystalline wax 7 11. Petroleum15 12. Dimethyl polysiloxane 3 13. Squalane 5 14. Isopropyl palmitate 1715. Antioxidant suitable amount 16. Perfume suitable amountPreparation Process

Constituents 9-15 were kept at 85° C. for dissolution, to which wasadded a powder well mixed with stirring. The yield was then pulverizedwith a colloidal mill for dispersion. Then, constituent 16 was added tothe mixture and the yield, after deaeration, was poured into a vessel at70° C., and cooled to give a foundation of Example 8.

The same process as used to produce the oily stick foundation of Example8 was employed, except that a powder obtained in Comparative Example 4was used, instead of a powder obtained in Example 4, to give apreparation of Comparative Example 7.

Example 8 and Comparative Example 7 were applied to the skin, and theresulting stains were evaluated immediately after application by visionfor how notable their whiteness is. The evaluation was ranked as above.The results are shown in Table 9.

TABLE 9 Example 8 Comparative Example 7 Transparency ◯ Δ

From the results of Table 9 it is seen that Example 8 comprising acomposite of Example 4 provides a foundation whose whiteness looksnatural and plain even when observed immediately after its applicationto the skin, and thus ensures a fine finish. In contrast, ComparativeExample 7 containing a powder of Comparative Example 4 gives a notablewhite when applied to the skin. Moreover, it is more difficult to extendComparative Example 7 uniformly over the skin. From this it is obviousthat addition of silica sol improves the dispersibility of cerium oxideas well as of titanium oxide.

Additional exemplary cosmetic preparations containing the metaloxide/silica composite of this invention will be described below.

EXAMPLE 9 W/O sunscreen  1. Talc 6  2. The titanium oxide/silicacomposite 12 of Example 1 treated with stearic acid  3. Zinc oxidetreated with stearic acid 8  4. Octylmethoxy cinnamate 5  5. Liquidpetroleum 1  6. Decamethyl cyclopentasiloxane 26.8  7. Dimethylpolysiloxane 16  8. Polyoxyethylene modified 2 dimethylpolysiloxane  9.Ion exchanged water 15 10. 1,3-butylenes glycol 8 11. Antiseptic 0.1 12.Perfume 0.1(Manufacture of a Stearic Acid-Treated Powder)

To ethanol 100 parts was added stearic acid 5 parts for dissolution. Tothis mixture was added a powder 20 parts for mixture. The resultingdispersion was heated with stirring at a temperature of 90° C. orhigher, to allow the solvent to evaporate, which yielded a stearicacid-treated powder.

Production Method

Constituents 4 to 8 were heated at 70° C. for mixture to give an oilphase. In a separate run, constituents 10 and 11 were added toconstituent 9 for dissolution to give a water phase. To the oil phasewere added powdery constituents 1 to 3, and the powder was dispersedwith a homogenizer. To the yield was added the water phase, which wasthen emulsified with a homogenizer. To the yield was added constituent12, and the mixture was poured in a vessel.

EXAMPLE 10 Solid powder foundation  1. Silicone treated talc 11.4  2.Silicone treated mica 41  3. Silicone treated titanium dioxide 10  4.The titanium oxide/silica composite 10   of Example 1 treated withsilicone  5. The cerium oxide/silica composite 8 of Example 3 treatedwith silicone  6. Silicone treated red iron oxide 1  7. Silicone treatedyellow iron oxide 3  8. Silicone treated black iron oxide 0.2  9. Nylonpowder 2 10. Dimethyl polysiloxane 8.5 11. Octylmethoxy cinnamate 1 12.Polyoxyethylene modified 0.6 dimethylpolysiloxane 13. Polyoxyethylenesorbitan monooleate 1 14. Isocetyl octanoate 2 15. Ethyl paraben 0.2 16.Perfume 0.1Production Method

Constituents 10-15 were heated for dissolution (which was made an oilphase). In a separate run, constituents 1-9 were mixed with a blender,and the yield was mixed with the oil phase. Constituents 16 was sprayedinto the mixture, and mixed to uniformity. The yield was pulverized witha miller, placed into a medium-sized plate, and molded under pressure.

EXAMPLE 11 W/O foundation  1. Sericite 5  2. Kaolin 4  3. Titaniumdioxide 6  4. Red iron oxide 0.36  5. Yellow iron oxide 0.8  6. Blackiron oxide 0.16  7. The zinc oxide/silica composite 4 of Example 4  8.Liquid petroleum 5  9. Decamethyl cyclopentasiloxane 29 10.Polyoxyethylene modified 4.5 dimethylpolysiloxane 11. Ion exchangedwater 36 12. 1,3-butylenes glycol 5 13. Antiseptic 0.1 14. Perfume 0.08Production Method

Constituents 8-10 were heated at 70-80° C. for dissolution (which wasmade an oil phase). In a separate run, to constituent 11 were addedconstituents 12 and 13 (which was made a water phase). Constituents 1-7were mixed, to which was added the oil phase, and the yield was mixedwith a homomixer. To the yield was added constituent 14 for mixture, towhich was added the water phase for emulsification, and the yield waspoured into a vessel.

EXAMPLE 12 Lipstick  1. The titanium oxide/silica composite 10 ofExample 2  2. Red 201 0.6 (Lithol Rubine B (D & C Red No.6))  3. Red 2021 (Lithol Rubine BCA (D & C Red No.7))  4. Red 223 0.2(Tetrabromofluorescein (D & C Red No.21))  5. Candelilla wax 9  6. Solidparaffin 8  7. Beeswax 5  8. Carnauba wax 5  9. Lanolin 11 10. Castoroil 23.2 11. 2-ethylcetylhexanoate 17 12. Isopropyl myristate 10 13.Antioxidant suitable amount 14. Perfume suitable amountProduction Method

Constituents 1-3 were mixed with a part of constituent 10, and the yieldwas treated with a roller (the yield was made a pigment). Constituent 4was dissolved into a part of constituent 10 (the yield was made a dye).Constituents 5-13 were mixed, and heated for dissolution, to which wereadded the pigment and the dye. The yield was mixed with a homomixer tosuch an extent as to make the constituents thereof to be uniformlydispersed. The yield was poured in a die, and suddenly cooled to give astick-like mold.

EXAMPLE 13 W/O emulsified sunscreen (liquid type)  1. Talc 3.0  2. Thetitanium oxide/silica/alumina 12.0 composite of Example 5  3. Bentonite0.5  4. Polyoxyethylene sorbitan monostearate 0.9  5. Triethanolamine1.0  6. Propylene glycol 10.0  7. Ion exchanged water 51.1  8. Stearicacid 2.2  9. Isohexadecyl alcohol 7.0 10. Glycerin monostearate 2.0 11.Liquid lanolin 2.0 12. Liquid petroleum 8.0 13. Antiseptic 0.2 14.Perfume 0.1Production Method

Constituent 3 was dispersed in constituent 6; the yield was added toconstituent 7; and the yield was heated to 70° C. and then stirred witha homomixer. Then, to the yield were added constituents 4 and 5, to givea water phase. In a separate run, constituents 8-13 were heated to70-80° C. for dissolution, to give an oil phase. To the water phase wereadded constituents 1 and 2 with stirring, and the yield was treated witha homomixer at 70° C. To the yield was gently added the oil phase keptat 70-80° C., and the yield was treated with a homomixer at 70° C. Aftercooling, the yield was mixed with constituent 14, and the yield waspoured into a vessel.

According to this invention, it is possible to obtain a cosmeticpreparation in which particles of metal oxide have an improveddispersibility and in which fine particles satisfactorily exert theircharacteristic activities such as UV protection, by adding, to a basematerial, a metal oxide/silica composite which is obtained by mixingfine particles of metal oxide having a primary particle diameter of1-1000 nm with silica particles to allow the two kinds of particles tointimately disperse into each other, such that the metal oxide particlesexist substantially as primary particles.

1. A metal oxide/silica composite wherein metal oxide particles whoseprimary particle diameter is 1-1000 nm are co-dispersed fine with silicaparticles, and the metal oxide particles exist substantially as primaryparticles in the composite, wherein the composite is obtained by (a)mixing the dispersion with the fine particles of metal oxide or its sol,(b) altering the pH of the resulting mixture solution, and (c) exposingthe resulting solution to a temperature between 80-120° C. so as tocause the silica particles to condense and the condensed silicaparticles and the metal oxide to aggregate for deposition wherein saidsilica particles are condensed thereby not maintaining in their initialstate.
 2. The metal oxide/silica composite as claimed in claim 1,wherein the composite is obtained by mixing (1) a dispersion comprisinga silica sol where silica particles have a primary particle diameter of1-150 nm, and (2) fine particles metal oxide whose primary particlediameter is 1-1000 nm, or a sol of the same metal oxide.
 3. The metaloxide/silica composite as claimed in claim 1, wherein the metal oxideexisting as fine particles or a sol consists of one, or two or moreselected from a group consisting of titanium oxide, zinc oxide, andcerium oxide.
 4. The metal oxide/silica composite as claimed in claim 1,wherein the metal oxide/silica composite exists in a gel form.
 5. Themetal oxide/silica composite wherein the composite is in a powdery formobtained by further drying the gel form of said metal oxide/silicacomposite as claimed in claim
 4. 6. The metal oxide/silica composite asclaimed in claim 1, wherein the composite comprises 5-90 wt % metaloxide with respect to the total weight of the composite.
 7. A cosmeticpreparation comprising the metal oxide/silica composite as claimed inclaim
 1. 8. The metal oxide/silica composite as claimed in claim 1,wherein said metal oxide particles are stably dispersed in said metaloxide/silica composite.